Self focusing of laser beams in plasmas and semiconductors pdf

Self focusing of laser beams in plasmas and semiconductors sodha, m. Selffocusing of laser beam in collisional plasma and its effect on. The shadowgraphy study of the onset of relativistic selffocusing using 0. Focusing of a dark hollow gaussian electromagnetic beam in a. Self focusing of intense short laser pulse in cluster plasma. My question, however, is still an objective and definable one, which is more or less can the above laser cut steel with the appropriate lens. May 20, 2011 read self focusing of gaussian laser beam through collisionless plasmas and its effect on second harmonic generation, journal of fusion energy on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Index terms acceleration, gases, laser beam focusing, op.

It means self focusing reduces the threshold for the occurrence of other nonlinear optical processes. Selffocusing of an intense optical beam in a plasma is stud. The laser induces modifications of the plasma refractive index via relativistic and ponderomotive nonlinearities. Relativistic selffocusing of intense laser beam in thermal. Tripathi indian institute of technology, hauz khas, n e w delhi110029,india work supported by national science foundation, u. Effect of absorption coefficient and plasma density on the beam. We will rst discuss instabilities, then beam self focusing, and nally self trapping. We drive the equation of beam width parameter by using parabolic wave equation. Dispersion of nondegenerate nonlinear refraction in semiconductors. Selffocusing of an ellipticgaussian laser beam in relativistic ponderomotive plasma using a ramp density profile. Selffocusing of electromagnetic beams in semiconductors d p tewari and b l patheja physics department, indian institute of technology, new delhi1 10029, india received 6 april 1978, in final form 21 june 1978 abstract. V self focusing of laser beams in plasmas and semiconductors.

Improving the relativistic selffocusing of intense laser beam in plasma using density transition article pdf available in physics of plasmas 168. Self focusing of laser beams in plasmas and semiconductors. As a result, the incident laser beams become self focused due to the nonlinearity by the ponderomotive force. Propagation of a gaussian xray laser beam has been analyzed in collisionless thermal quantum. Relativistic self focusing of tw laser pulses in high density gas jet targets. With the availability of high power laser beams, a large number of interesting nonlinear phenomena. Nonlinear differential equation for beam width parameter of laser beam has been set up and solved numerically to study the variation of beam width parameter with normalized distance of propagation. We study the selffocusing and defocusing of a light beam carrying angular momentum called twisted light propagating in a nonlinear medium. The study of the phenomena related to selffocusing of intense laser light propagating in plasma. Selffocusing of laser beams in dielectrics, plasmas. Formation of plasma channels has numerous applications including tabletop x ray lasers and laser plasmaproduced particle accelerators. We study the self focusing and defocusing of a light beam carrying angular momentum called twisted light propagating in a nonlinear medium. Intl workshop on nonlinear phenomena in vlasov plasmas, cargese, france 1988.

Second harmonic generation of selffocused chirped laser. Read parametric dispersion and amplification in semiconductor plasmas. Self focusing of an intense optical beam in a plasma is stud. Selffocusing of gaussian laser beam through collisional. Self focusing effect imposes a limit on the power that can be transmitted through an optical medium. Electromagnetic beam profile dynamics in collisional plasmas. Laser annealing of semiconductors deals with the materials science of surfaces that have been subjected to ultrafast heating by intense laser or electron beams. Effect of absorption coefficient and plasma density on the beam width. Because of selffocusing of the fundamental laser pulse, a transverse intensity gradient was created, which generated a plasma wave at the fundamental wave frequency. This effect is important for laser selffocusing in semiconductors. Tajima department of physics and institute for fusion studies, the university of texas at austin, austin, texas 78712 received 21 march 1989 self focusing of an intense optical beam in a plasma is studied, including the nonlinear effects of. A unied approach to selfaction effects is given in 27. As a result, the incident laser beams become selffocused due to the nonlinearity by the ponderomotive force.

Physics bulletin, volume 26, number 5 download article pdf. Lawrence livermore national laboratory, livermore, colifornia 94550 received may 5, 1987. For large laser power below the critical power of relativistic selffocusing. Tajima department of physics and institute for fusion studies, the university of texas at austin, austin, texas 78712 received 21 march 1989 selffocusing of an intense optical beam in. Self focusing of electromagnetic beams in semiconductors d p tewari and b l patheja physics department, indian institute of technology, new delhi1 10029, india received 6 april 1978, in final form 21 june 1978 abstract. The nonlinear interaction of highpower multicolor laser beams in plasmas is investigated numerically. Self focusing of hermitecoshgaussian hchg laser beam in semiconductor quantum plasma scqp has been presented by considering the decentred parameter and quantum effect.

Chapter 4 fundamentals of lasermaterial interaction and. The relativistic effect of selffocusing on the secondharmonic generation of a chirped pulse laser in a preformed plasma channel has been studied. Also, it is realized that in a dense plasma environment, the laser selffocusing. We will rst discuss instabilities, then beam selffocusing, and nally selftrapping. However in studying the self focusing of hermitegaussian laser beams in plasma under plasma density ramp by kant et al. In this paper, we show the self focusing and spot size evolution of the laser beams in semiconductor plasmas. It means selffocusing reduces the threshold for the occurrence of other nonlinear optical processes. A continuous wave laser beam is represented by the number 100 while 103, 106, 109, and 1012 seconds represents millisecond, microsecond, nanosecond, and picosecond time scales, respectively. Oct 19, 2015 furthermore, it is found that there exists a certain intensity value below which the laser pulse tends to self focus, while the beam diverges above of this value. Anonymous coward gave a good reference, which is a guide to gaussian optics. Effect of pulse slippage on density transitionbased resonant. The previous chapter was concerned with laser and particle beams insofar as they are used to produce hed plasmas, whereas this chapter is concerned with the physics of the beamplasma interaction itself. The understanding of laser beam propagation through underdense plasmas is of vital importance to laser plasma interaction experiments, as well as being a fundamental physics issue.

Selffocusing of the fundamental laser pulse enhances the. This chapter discusses a unified treatment of self focusing in plasmas and semiconductors. The instabilities of nonlinear origin in the plasma are enhanced by the enhancement of the intensity of the beam due to self focusing. The resonant thirdharmonic generation of a selffocusing laser in plasma with a density transition was investigated. The fast ignitor concept, for example, requires the formation of an evacuated. His foundational contribution was the realization that coherent molecular oscillations resulted from stimulated raman scattering, leading to the introduction of stimulated brillouin scattering. Detection technique for selfmodulation of long electron beams in plasmas marcin sliwa, university of oxford, uk september 11, 2014 abstract selfmodulation of particle beams in a plasma is considered as a concept enabling plasma wake eld acceleration with long driver beams. Keywords self focusing, plasma density, nonlinearity, hermitecoshgaussian beam. The fast ignitor concept, for example, requires the formation of. Chen, laser driven mode coupling of ion and electron waves, proc. In the present paper, selffocusing of gaussian laser beam through collisional plasma is studied by moment theory approach. Selffocusing and defocusing of gaussian laser beams in.

Propagation of an intense laser pulse in plasma with a periodically modulated density is considered using envelope equations. Selffocusing and defocusing of twisted light in nonlinear media. Relativistic gaussian laser beam selffocusing in collisional. Formation of plasma channels has numerous applications including tabletop x ray lasers and laserplasmaproduced particle accelerators. Tajima department of physics and institute for fusion studies university of texas at austin austin texas 78712 abstract. Organic semiconductors are made of carbon and hydrogen, and hence are also advantageous for producing plasma with light ions and less mobile electrons. Selffocusing effect imposes a limit on the power that can be transmitted through an optical medium. Milchberg, self focusing of intense short laser pulse in cluster plasma, in conference on lasers and electroopticsquantum electronics and laser science conference, technical digest optical society of america, 2003, paper cwa37. Both the relativistic mass increase and the driven plasma wave contribute to the mutual beambeam interaction and to the development of the electromagnetic cascade. Nonlinear optics was profoundly influenced by early work of charles townes and his group at massachusetts institute of technology from 1961 to 1967. The monoenergetic elec tron beams, which are produced in laserplasma acceler. This control is exercised throughthe properselection of laser processing parameters to achieve the desired material modi. Selffocusing, channel formation, and highenergy ion. A unied approach to self action effects is given in 27.

This book is organized into chapters that specifically tackle transient annealing of compound semiconductors. The propagation of ultrashort high intensity laser pulses in underdense plasma is of interest for the understanding of laser interaction processes in a new relativistically driven plasma regime. The effects of terawatt laser beam self focusing and plasma channel formation have recently been observed using the laser probing technique. Such simulations must improve the understanding of important lasermatter interaction mechanisms multiphoton absorption and avalanche process, scattering effects, etc. The shadowgraphy study of the onset of relativistic self focusing using 0. Study of nonlinear ohmic heating and ponderomotive force effects on the selffocusing and defocusing of gaussian laser beams in collisional underdense plasmas. An analysis of self focusing of an elliptic gaussian laser beam, propagating through. A medium whose refractive index increases with the electric field intensity acts as a focusing lens for an electromagnetic wave characterized by an initial transverse intensity gradient, as in a laser beam.

Self, focusing of spherical gaussian beams as its primary reference. Self focusing of the fundamental laser pulse enhances the intensity of the second harmonic pulse. Beam nonparaxiality, filament formation, and beam breakup in. Selffocusing is a nonlinear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. The self focusing of an electromagnetic beam in parabolic and nonparabolic. Selffocusing of laser beam in collisional plasma and its effect on second harmonic.

Parametric dispersion and amplification in semiconductor. Also the focusing and defocusing of hchg beam in the plasma having dependency on decentred parameter and frequency of incident laser beam isreported. Selffocusing of hermitecoshgaussian laser beams in plasma. It is realized that the laser selffocusing in the quantum plasma. Relativistic selffocusing causes a shrinking of laser beams in high density plasmas down to one wavelength diameter within a penetration depth approximately equal to the diameter of the initial beam in vacuum before the plasma interaction. However in studying the selffocusing of hermitegaussian laser beams in plasma under plasma density ramp by kant et al.

Self focusing of laser beams in dielectrics, plasmas and semiconductors. Osa selffocusing and defocusing of twisted light in non. Self focusing of elliptic gaussian laser beams indian academy of. Selffocusing of hermitecoshgaussian hchg laser beam in semiconductor quantum plasma scqp has been presented by considering the decentred parameter and quantum effect. Effect of the intensity of the laser beamplasma density on the harmonic yield is studied in detail. Selffocusing of an ellipticgaussian laser beam in relativistic. Pdf external selffocusing of light by nonlinear layer researchgate. Search the leading research in optics and photonics applied research from spie journals, conference proceedings and presentations, and ebooks. Collisionless shocks in laserproduced plasma generate. Published 20 september 20 20 astro ltd laser physics letters, volume 10, number 11. Detection technique for selfmodulation of long electron. Self focusing is a nonlinear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. Self focusing of laser beams in dielectrics, plasmas and. Beam nonparaxiality, filament formation, and beam breakup in the selffocusing of optical beams m.

The method is based on the wentzelkramersbrillouin and the paraxial approximations. Laser beam propagation, filamentation and channel formation. Nov 21, 2012 in the present paper, self focusing of gaussian laser beam through collisional plasma is studied by moment theory approach. Enhanced focusing of laser beams in semiconductor plasmas. Attraction and repulsion of multicolor laser beams in. The selffocusing of an electromagnetic beam in parabolic and nonparabolic. We drive the equation of beam width parameter by using parabolic wave equation and solved it numerically by using wkb approximation. Feb 01, 2009 read parametric dispersion and amplification in semiconductor plasmas. Opportunities in higher order nonlinear laser interactions mildly relativistic intense laser pulses, with quiver electron velocity. This book treats the theory of nonlinear, self focusing of optical beams using the. Selffocusing of highpower laser beam through plasma. Contributions of charles townes research to nonlinear optics. Ghatak a k and tripathi v k 1968 self focusing of laser beams in dielectrics, plasmas and semiconductors new delhi.

Detection technique for self modulation of long electron beams in plasmas marcin sliwa, university of oxford, uk september 11, 2014 abstract self modulation of particle beams in a plasma is considered as a concept enabling plasma wake eld acceleration with long driver beams. We derive a differential equation for the beam width parameter f as a function of the propagation distance, angular frequency, beam waist and intensity of the beam. The understanding of laser beam propagation through underdense plasmas is of vital importance to laserplasma interaction experiments, as well as being a fundamental physics issue. Study of nonlinear ohmic heating and ponderomotive force effects on the self focusing and defocusing of gaussian laser beams in collisional underdense plasmas. Pdf the propagation characteristics of a gaussian laser beam through warm collisional plasma are investigated by considering the. Read selffocusing of gaussian laser beam through collisionless plasmas and its effect on second harmonic generation, journal of fusion energy on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Tripathi, self focusing of laser beams in dielectrics, semiconductors and plasmas, tatamcgraw. The effects of terawatt laser beam selffocusing and plasma channel formation have recently been observed using the laser probing technique. Laserdriven proton accelerators could enable more effective cancer treatment, but to fulfil this function proton beams with a higher energy and narrower energy spread will need to. Self focusing of a laser pulse in plasma with periodic.

This paper presents an investigation on the self focusing of a coshgaussian laser beam in the thermal quantum plasma tqp by taking into account the effects of relativistic nonlinearity. Furthermore, it is found that there exists a certain intensity value below which the laser pulse tends to self focus, while the beam diverges above of this value. Pdf ponderomotive selffocusing of gaussian laser beam in warm. In these applications, one needs the laser beam to propagate over several rayleigh lengths while preserving an efficient interaction with the plasmas. In addition, the results confirm that, by increasing the plasma and cyclotron frequencies plasma density and magnetic strength, the self focusing effect can occur intensively. Relativistic self focusing causes a shrinking of laser beams in high density plasmas down to one wavelength diameter within a penetration depth approximately equal to the diameter of the initial beam in vacuum before the plasma interaction. Weakly relativistic ponderomotive effects on selffocusing in the interaction of coshgaussian laser beams with a plasma. In this paper, we show the selffocusing and spot size evolution of the laser beams in semiconductor plasmas. Selffocusing of electromagnetic beams in semiconductors.

Attention is given to the kinetic theory of the fielddependent dielectric constant, steady state self focusing of electromagnetic beams in plasmas, nonsteady state self focusing, the growth of instability, and experimental investigations on self focusing. Relativistic selffocusing of tw laser pulses in high density gas jet targets. Laserplasma and beamplasma interactions frontiers in. Self focusing of laser beams in dielectrics, semiconductors and plasmas tatamcgrawhill. Weakly relativistic ponderomotive effects on selffocusing in. Selffocusing often leads to damage in optical materials so it is a limiting factor in the design of highpower laser system but it can be. Pdf improving the relativistic selffocusing of intense. Pdf relativistic gaussian laser beam selffocusing in. Self focusing of laser beams in dielectrics, semiconductors and plasmas tata mcgrawhill. Pdf selffocusing and guiding of short laser pulses in ionizing. In the region of high plasma density, the self focusing effect of nonlinearity suppresses the diffraction divergence, and the laser converges.